<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>列表过渡</title>
  <script type="text/javascript" src="vue.js"></script>
  <style>
    .list-item {
      display: inline-block;
      margin-right: 10px;
    }
    .list-enter-active, .list-leave-active {
      transition: all 1s;
    }
    .list-enter, .list-leave-to
    /* .list-leave-active for below version 2.1.8 */ {
      opacity: 0;
      transform: translateY(30px);
    }
  </style>
</head>
<body>
  <div id="app" class="demo">
    <button v-on:click="add">Add</button>
    <button v-on:click="remove">Remove</button>
    <transition-group name="list" tag="p">
      <span v-for="item in items" v-bind:key="item" class="list-item">
        {{ item }}
      </span>
    </transition-group>
  </div>

  <script>
    new Vue({
      el: '#app',
      data: {
        items: [1,2,3,4,5,6,7,8,9],
        nextNum: 10
      },
      methods: {
        randomIndex() {
          return Math.floor(Math.random() * this.items.length)
        },
        add() {
          this.items.splice(this.randomIndex(), 0, this.nextNum++)
        },
        remove() {
          this.items.splice(this.randomIndex(), 1)
        },
      }
    })
  </script>
</body>
</html>